1. Field of the Invention
The present invention relates generally to internal combustion engines, and specifically to separation of oil from crankcase gases of internal combustion engines.
2. Description of Related Art
In automobile racing, and especially in the sport of drag racing, horsepower is very important. Drag races are often decided by thousandths of a second. Even small gains in engine efficiency can lead to victory. One well known method of increasing engine efficiency in the art of engine building is to run a vacuum pump on the crankcase side of the engine. Crankcase gases are often evacuated to a “breather,” which is typically a reservoir with a fiber-based filter element on top. Although these vacuum systems are successful in increasing horsepower, oil particles are typically exhausted from the “breather” at a high rate. This condition pollutes, creates a fire risk, and causes unsafe conditions on race tracks. Because of the way current systems are designed, an oil mist accumulates in the engine compartment (on the engine, underside of the hood and firewall). One of the most annoying responsibilities of a crew chief for drag racing is cleaning the engine compartment between races. If not cleaned between races, this accumulated oil can cause a fire hazard.
The most common vacuum systems for internal combustion engines are belt driven centrifugal pumps. These pumps are typically driven by the crankshaft. They draw crankcase gases from fittings on valve covers or from the oil valley. The gases are a mixture of the products of combustion that flow past the pistons (“blow-by gases”) and air filled with atomized oil particles created by the rotating action of the crankshaft. Although these systems add weight to a vehicle, in drag racing the net increase in horsepower is thought to offset the undesirable effect of the additional weight. State-of-the-art vacuum systems are commercially available from Aerospace Components of St. Petersburg, Fla. and Moroso of Guilford, Conn., for example.
Water-cooled engines also need overflow volume for expansion of fluid in the cooling system as the engine heats. This is normally a separate accumulator system on a race car. It requires a second mounting area, extra weight, and reduces the amount of space in the engine compartment area. Current systems on racecars have several parts that work together in an attempt to separate air, oil and water. These include: an oil/air separator prior to the vacuum pump, an atmospheric air volume regulator (pressure regulator) prior to the vacuum pump, an oil accumulator tank, a breather filter on top of the oil accumulator, and a water accumulator for overflow.
The need for oil-air separators has been felt since the advent of the internal combustion engine. U.S. Pat. No. 973,118, dated Oct. 18, 1910, discloses an apparatus that draws gases out of the crankcase, and recycles those gases into the intake of the cylinders. This early form of the oil-air separator took the form of “a pipe . . . to maintain the air free of oil or dirt . . . . ”
U.S. Pat. No. 5,063,882, titled “Oil Separation for Gases from a Crankcase of an Internal Combustion Engine,” to Dr. Ing.h.c.F. Porsche. Aktiengesellschaft discloses an oil separator based on a labyrinth comprising two deceleration paths for oil contained in crankcase gases.
U.S. Pat. No. 6,167,849 discloses an oil collector particularly adapted to motorcycles. It is said to cool blow-by gases containing oil vapor and particles and then to discharge the gases to the atmosphere through a filter, which is not described, but appears to be conventional pleated air filter.
U.S. Patent Application Publication No. 2008/0047505 A1, titled “Oil Separator Element,” discloses an oil separator element that operates by setting crankcase gases in rotational motion so that centrifugal forces cause oil droplets to form on the walls of the grooves in the filter element.
What is needed, especially for race cars, is a system that combines the oil/air/water separation into one unit. Not only could this system eliminate the need for all the separate systems listed above, it would also reduce the weight of the car (each piece above plus all their brackets, clamps). With only one unit (compared to six separate pieces) required to accomplish the tasks, adjustments and replacements would also be much simpler. For race cars, and for crankcase gases from all internal combustion engines, including those in all vehicles and stationary engines, there is a need for a more effective, economical apparatus to separate the oil in crankcase gases from the gas phase and accumulate the separated oil.